Process for producing long pasta products

ABSTRACT

A process for producing long products with a moisture content of less than approximately 14% by weight and particularly approximately 11 to 13% by weight is disclosed. The long product leaves the press head in the form of soft, moist-plastic dough strands being guided in suspended manner up to the final drying through varyingly heated climate zones and at the end of the drying process, the long product is cooled and/or dimensionally stabilized in a further climate zone. The long product leaving the press head is heated as rapidly as possible in a first climate zone to approximately 80° C. under the action of a heating medium with a relative humidity of approximately 60 to 80%. Then in a second climate zone under the action of a drying medium with a temperature of over approximately 80° C. and a relative humidity of approximately 65 to 85% the product is dried to a moisture content of less than approximately 14% by weight. This process can be performed extremely rapidly and supplies high-quality products. It can be performed with particular advantage in a single-level drier for drying the long products (FIG. 1).

This is a continuation of application Ser. No. 703,101 filed Feb. 15,1985, now abandoned.

TECHNICAL FIELD

The invention relates to a product for producing long products with amoisture content of less than approximately 14% by weight andparticularly approximately 11 to 13% by weight, the long product leavingthe press head in the form of soft, moist-plastic dough strands beingguided in suspended manner up to the final drying through varyinglyheated climate zones and at the end of the drying process, the longproduct is cooled and/or dimensionally stabilized in a further climatezone.

BASIC PRIOR ART

Pasta products, particularly long pasta products or long products, apartfrom raw cereals and/or bread, are the most widely encountered basicfoods and are extensively used particularly for storage or stockpilingpurposes. They are ready-to-cook, dry cereal products, which areproduced from wheat grits, dust or flour doughs, without using afermentation or baking process, by moulding and careful drying. On thebasis of the raw materials, a distinction is made between egg pastaproducts and egg-free pasta products, as well as grits and flour pastaproducts, whilst on the basis of their external appearances adistinction is made between noodles (ribbon macaroni, cut noodles andvermicelli), dumplings, macaroni (tubular noodles) and spaghetti. Themain raw materials of the pasta products are durum wheat grits or dusts,which have a constant particle size distribution, high protein content,high content of yellow pigments (xanthophyll or esters thereof) and goodpigment stability, whilst having a limited tendency to grey-browndiscolouration.

For the production of pasta products, a dough is prepared from thecereal raw materials--grits or dust, usually mixed with one another andwhen the supply situation is unfavourable also flour, whilst also addingapproximately 26 to 32% water, optionally salt, egg for dietetic pastaproducts, together with gluten and other protein products, shapingtaking place by pressing or rolling and cutting, followed by the finaldrying. The water quantity and temperature, the mixing or kneading timeand the control of drying are dependent on the nature of the rawmaterial mixtures, the production principle and the specialcharacteristics of the available machinery. The freshly shaped pastaproduct contains on average approximately 31% moisture, whereas thecompletely dried and packed product only contains approximately 11 to13%.

In connection with the aforementioned pressing, it is fundamentallypossible to adopt two different process procedures: (a) the older batchprocess with the production of homogeneous, plastic doughs in aprekneader and grinding mill and shaping in hydraulic presses, or (b)according to the modern continuous process with so-called screw presses,in which no homogeneous part is kneaded in the first section and insteadmerely a lumpy or crumbly dough material is formed in troughs usingmixing paddle mechanisms and this is slowly passed on by conveyor screwsand is supplied to the press head. It is only the shear forces in thepressout screw, as well as the high pressures of approximately 100 to150 bar prevailing in the press chamber and during the passage of thedough through the die that bring about the necessary homogeneouskneading or "cementing" of the dough. The homogenized, kneaded,moist-plastic dough is forced out of the die in the form of a constantflow of completely shaped and structurally strongly compressed doughstrands. A blower immediately dries the surface of the discharged doughstrands, in order to remove their stickiness. Rotating blades can bepositioned directly below the die and they cut the preshaped strands tothe desired length. The strands obtained in this way must be dried forproducing a durable product, the drying progressing from the outside tothe inside. It is important that the surface does not harden too longbefore the core, in order to prevent cracks and flaws in the finishedpasta product. The freshly shaped pasta product has a water content ofapproximately 31%. As a result of the surface drying after leaving thepress head scarcely 1% water is lost.

The control of the drying process still takes place on the basis ofexperience originally acquired in the Mediterranean area when drying inthe open air with the cyclic changes of air movement, temperature andhumidity which naturally occur there. The drying time during this dryingprocess from shaping up to obtaining the final moisture content of thepasta product was 3 to 5 days, both for short and long pasta products.

During industrial production, the aforementioned drying conditions weresimulated to the maximum possible extent, whilst seeking processoptimization and in particular an acceleration of the drying process.This revealed numerous problems. Thus, the drying of the shaped dough isthe final and technologically most problemmatical part of pastaproduction, particularly when in the form of long pasta products. Thus,it is a question of so controlling the water removal that the dryingadvances from the outside to the inside in such a way that the surfacedoes not harden before the core, in order to prevent cracks and flaws inthe finished pasta. This means that the surface should not harden beforethe core and that the moisture gradient between the layers should belimited. Drying at too high a temperature, low relative atmospherichumidity and strong air circulation leads to shrinkage stresses, whichsubsequently bring about cracks and flaws, together with adisintegration of the dry pasta products or a disintegration on cookingin pieces. Excessively slow drying at medium temperature, high relativeatmospheric humidity and weak air circulation leads to radial distortionof the long pasta products hanging on the bars. This slow drying canlead to leavening.

It is clear that many points must be taken into consideration during theoptimization of the drying of the long products.

Up to roughly one or two decades ago, a long product was only consideredto be qualitatively completely satisfactory, if the drying temperaturedid not exceed 50° C. and the drying period was at least 18 to 24 hours.Of late, roughly the following procedure has been adopted. The longproducts leaving the press initially pass in a meandering manner througha predrier. Within 1 to 3 hours, the water content drops steeply to 20to 24%, i.e. in the critical region of the pasta products passing fromthe plastic into the solid state. At this boundary, there is a sweatingperiod which lasts several hours during which the treated product passesthrough drier zones without moisture removal. The residual water can beuniformly distributed from the core over the entire cross-section of theindividual shaped pieces. The following final drying takes place moreslowly and carefully than the predrying to a moisture content ofapproximately 11 to 13%. The warm, dry long product can still pass onthe bars in the storage bins and remains there for several hours andoptionally overnight, in order to remove residual stresses in themoisture equilibrium with approximately 55 to 65% relative atmospherichumidity at ambient temperature or slightly above the latter. The thus"stabilized", i.e. less pressure-endangered finished product, is thendelivered to the packing machines.

According to the present prior art, drying takes place for 8 to 12 hoursat a temperature of 70 to 75° C. Although Swiss Patent No. 303,652refers to a treatment temperature of up to 110° C., this known processis controlled in such a way that pasting of the pasta product takesplace. Inter alia, this leads to a reduction of quality. Due to theproblems indicated therein at higher temperatures, as yet no process isknown permitting a drying at higher temperatures and with short dryingtimes, because hitherto an increase in the temperatures has always ledto quality losses, particularly with respect to the appearance of theproduct (colour, surface characteristics). However, a high dryingtemperature also appeared disadvantageous for the following reasons.When the long products pass 8 to 12 hours in the drier, faults e.g. inthe conveying system have a very serious impact. Thus, not only can acomplete day's production of 15 to 20 t of pasta products in the case oflarge plants become unusable, but the complete pasta material must beindividually manually removed from the bars of the conveying means.Thus, in the case of higher temperatures, the complete installation mustbe cooled to an acceptable temperature prior to the elimination of amechanical fault in the interior.

Of late, various attempts have been made to optimize the production oflong pasta products. As in many natural products, the hitherto stepwisegroping towards a different technology solution was extremely difficultor even doomed to failure, because consideration had to be given to toomany influencing parameters and for systematic reasons only 1 or 2parameters could be changed in each test. Thus, the optimum point wasoften surprisingly far removed from the standard practice. However, allthe intermediate variations of the parameters only led to inferiorresults. Therefore, hitherto in connection with long products, atemperature of 80° C. has been looked upon much as a sound barrier forobtaining qualitatively high-grade products and it was considereddisadvantageous to exceed this temperature. This was attributed to thefact that the gluten protein, which can represent 70 to 80% of theprotein content, is even more extensively denatured during eachtemperature increase. This was proved by solubility tests, e.g. withdilute acetic acid. Protein coaggulation advanced rapidly attemperatures over 50 and up to 60° C. Deficient products were alwaysobtained in the many practical tests made to exceed temperatures of over60° C. People with a particularly highly developed taste-differentiatingevaluation capacity stated that the long products had a rubbery textureon biting and a low acidity was established. Thus, the consumer refusedlong products produced in this way. It is no longer possible toestablish what were the decisive criteria which have hitherto preventedthe introduction of a process for drying and producing qualitativelyhigh-value and particularly colour-perfect long products in atemperature range of approximately 80° to 100° C.

DISCLOSURE OF THE INVENTION

The problem of the invention was to so improve the aforementionedprocess, that it could be performed in a substantially troublefreesimple, economic and particularly rapid manner, whilst maintaining thequality standard expected of the product. In addition, the inventionproposes a suitable apparatus for performing this process.

According to the invention, this problem is solved in that the longproduct leaving the press head is heated as rapidly as possible in afirst climatic zone, but in more than 10 minutes to a temperature ofmore than approximately 80° C. under the action of a heating medium witha relative humidity of approximately 60 to 80% and then in a secondclimate zone under the action of a drying medium with a temperature ofover approximately 80° C. and a relative humidity of approximately 65 to85% is dried to a moisture content of less than approximately 14% byweight, or to avoid undesired reactions over approximately 80° C.initially to a moisture content of less than approximately 18% by weightand then at a lower temperature to a final moisture content of less thanapproximately 14% by weight.

The apparatus according to the invention is characterized in that thelong product drier is constructed as a single-level drier, which has arapid heating zone and an intense drying zone.

According to the process of the invention, a long product with amoisture content of less than approximately 14% by weight andparticularly approximately 11 to 13% by weight is sought. In manycountries, there are legal requirements concerning the final moisturecontent, so that in Switzerland and the Federal Republic of Germany avalue of approximately 12.5% by weight is required. From the purelytechnical standpoint (and also as a quality requirement), the levelshould always below approximately 14% by weight. Generally, there shouldbe no drop below a moisture content of 11% by weight, because drying attoo high a temperature is equivalent to a weight loss with respect tothe legal values. The value of approximately 12.5% by weight can belooked upon as optimum.

The starting material for the process according to the invention is thepartially plasticized or moist-plastic soft dough strands leaving apress head. When the present invention refers to "plastic", it is to beunderstood to mean a physical state, which inter alia is a function oftemperature and moisture content. The term plasticity is fundamentallyunderstood to mean the property of solid materials to undergo permanentdeformations under the action of external forces. The moist-plasticdough strands generally leave the press head at a temperature ofapproximately 40° to 50° C. Higher temperatures are to be avoided,because they give rise to undesired changes in the product to be dried,which impairs the finished product quality.

According to a preferred development of the process according to theinvention, after leaving the press head, the dough strands undergosurface treatment by an air stream, accompanied by a moisture loss ofapproximately 1 to 2% by weight. This inter alia removes an undesiredmoisture formed between the dough strands and in this way a certainclimatic stabilization is achieved. The ventilating air can bepreferably brought to approximately 40° to 60° C. to prevent the coolingto roughly 30° C. which generally occurs. Such a cooling would have tobe compensated again in the following rapid heating zone, which would becontrary to the objective of the invention. The treatment withventilating air following the press head generally lasts approximately 6to 10 minutes and leads to a surface drying. This measure can prevent"drop formation" which occurs in individual cases.

The dough strands leaving the press head and which may have undergonesurface treatment with ventilating air in the aforementioned manner areplaced mechanically over a bar attachment means and are then directlycut on reaching the desired leg length (accompanied by the formation ofa U-shape). The dough strands are cut in such a way that there is anadaptation to the dimensioning of the following units in the heating anddrying means.

A necessary requirement of the process according to the invention isthat the dough strands leaving the press head and cut to the desiredlength on the bar attachment means are subject to rapid heating to atemperature of more than approximately 80° C. Rapid heating generallytakes place in a range of approximately 80° to 140° C., particularlyapproximately 80° to 120° C. and in a particularly preferred mannerapproximately 95° to 120° C. The time during which rapid heating takesplace is obviously dependent on the sought final temperature, as well asthe temperature conditions on heating. However, it should be at leastapproximately 15 minutes, preference being given to the range 15 to 60minutes and in particular preference to the range 15 to 30 minutes. Theheating medium is air with a relative humidity of approximately 60 to85%, preference being given to the range of 65 to 75%.

On setting the desired minimum temperature of approximately 80° C.,various conditions must be respected in connection with the rapidheating. If the temperature in the first climate zone, in which rapidheating takes place, is identical to the sought final temperature, thiscould lead to the colder dough strands exhibiting a considerablecondensing out of water, so that an excessive film of water is formed.Although the water of this film could to a certain extent be absorbed bythe dough strands, it would not be possible to prevent an undesiredcaking. In addition, the so-called dripping or dropping could occur,which is also undesired. However, if the heating temperature wascontrolled in such a way there in the first climate zone that it wasvery close to the particular product temperature, then as a result ofthe limited temperature difference the rapid heating necessary forachieving the objectives of the invention would not be possible or wouldscarcely be possible and there would be considerable drying during theheating period and said drying should in fact take place in thefollowing treatment in the second climate zone.

In order to achieve an optimum process guidance in the first climatezone in the sense of the invention, thereare preferably temperaturejumps in said first climate zone. The optimum number of temperaturejumps is dependent on the particular sought minimum temperature. Four ormore temperature jumps are considered to be advantageous. If e.g. aminimum temperature of approximately 95° C. is sought, then it isadvantageous in each case to choose four or more temperature jumps. Theprocesses of moistening by condensation phenomena and drying take placein the individual zones of the different temperature jumps on thesurface of the long products in the form of moist, soft-plastic doughstrands. It must be ensured that moistening does not lead to theexcessive formation of an aqueous film with the aforementioneddisadvantageous phenomena, e.g. dripping. Thus, it is advantageous ifthe wet bulb temperature (dew point) of a following higher temperatureclimate zone is below the dry bulb temperature of the preceding climatezone. In other words, the temperature of the air introduced into thefollowing climate zone must not be raised above the wet bulb temperaturedifference ΔT. If this condition is respected, then the otherwiseundesired water vapour condensations occurring to a considerable extenton the walls of the container of the first climate zones are largelyprevented. If water vapour condensed on the walls, it could drop ontothe heated dough strands and lead to various disadvantageous effects,such as e.g. the aforementioned dripping. On optimizing the processaccording to the invention in the first rapid heating climate zone, thesum of the individual ΔT values (wet bulb temperature difference of theindividual, differently temperature-controlled climate zones) would bethe same or slightly higher than the total temperature rise of e.g.approximately 40 to 50% to at least approximately 80%.

On proceeding in the aforementioned manner in the first climate zoneusing at least one or preferably several and in particular more thanfour temperature jumps, then the sought rapid heating would be achieved,whilst minimizing the drying effect, so that the completely heated doughstrands regularly have a moisture content of approximately 24 to 27% byweight at the end of the first climate zone.

However, the aforementioned advantageous rapid heating utilizingtemperature jumps in the first climate zone in no way represents thesole possibility. As is readily apparent to the Expert, rapid heatingcan take place in many different ways. Thus, it would fundamentally alsobe conceivable to regulate the ambient temperature medium in the form ofe.g. air with the aforementioned moisture content in such a way thatthere is a gradual (continuous) temperature profile, but which has anadequate difference compared with the temperature profile of thematerial to be heated in order to achieve the sought rapid heating. Thismeans that there is an adequate temperature difference between theproduct and the surrounding heating medium at all points of the heatingzone. In order to extensively suppress the drying effect in the firstclimate zone which cannot be completely prevented, it is advantageouswithin the scope of the invention to set the relative atmospherichumidity in the heating climate to approximately 60 to 85%. In thiscase, heating could take place with superheated steam. At the end ofheating, there is still a substantially soft, moist and partiallyplasticized material.

On treating the long products in the first climate zone, as well as inthe following climate zones, it has proved particularly advantageous ifthe air stream in the various climate zones is zonally directed at rightangles to the long products and part of the air is introduced andremoved in the sense of a turbo-system through ducts inside and outsidethe drying area for the purpose of controlling the climate of theparticular climate zones.

The long product leaving the first climate zone with a temperature ofmore than approximately 80° C. is subsequently subject to an extremelyrapid drying at this elevated temperature and in the plastic state. Themain drying always takes place in the second climate zone, in which thedrying medium has a relative humidity of 65 to 85% and preferably 70 to80%. The original moist or soft-plastic material is subject to a moreextensive plasticization and in the final stage a thermoplastic productis obtained. If the latter is cooled to ambient temperature, it exhibitsstability. It is generally recommended to maintain the producttemperature set in the first climate zone in the second climate zone.Reference is made in this connection to the temperatures of temperatureranges mentioned in connection with the first climate zone. Thetreatment time is selected as a function of the treatment temperature inthe second climate zone. This treatment time show regularly be 30minutes or more and generally the range 30 to 120 minutes isadvantageous. Particular preference is given to the range 30 to 60minutes. These are particularly preferred times for the dryingtemperature of approximately 80° to 100° C., particularly 85° to 95° C.This provides a process product with the desired moisture content ofapproximately 14% by weight, particularly 11 to 13% by weight.

As a function of the starting material used, in individual casesundesired reactions can take place at elevated temperature, particularlyif thermally unstable additives, such as e.g. egg additives, milkproteins, etc or raw fibres are admixed with the dough and then dryingat lower temperatures is necessary to maintain the final quality.Preferably, the long product is intensely dried in less than 1 hour to aproduct moisture content of approximately 18% and then for 1 to 4 hours,preferably 2 to 3 hours and at a temperature of approximately 75° C. tothe final moisture content of less than 14%. It is appropriate in suchcases to initially lower the moisture content in the drying temperaturerange to approximately 18%. The now thermoplastic product is treated inthe following third climate zone at such a reduced temperature that theundesired browning reactions and other reactions are largely excluded,whilst ensuring a relatively rapid performace of the process, whilstmaintaining a high quality product. At this reduced temperature, themoisture content is set at less than approximately 14 % by weight,preferably approximately 12.5% by weight. It has been found that thelatter drying measure is advantageously performed at a temperature belowapproximately 75° C. The comments made hereinbefore regarding the dryingmedium of the second climate zone, particularly with respect to therelative atmospheric humidity apply accordingly. As the undesiredbrowning reactions take place to a greater extent with dropping moisturecontent and at high temperatures, it can be advantageous to provide oneor more temperature jumps in the third climate zone. The additionalfinal drying in the aforementioned third drying zone generally lastsapproximately 2 hours at 75° C. and approximately 4 hours atapproximately 65° C Whilst attempting to avoid further drying, the longproduct is then cooled to maintain the sought moisture content.

The cooling of the completely dried long product can e.g. take place ina cooler with subsequent stabilization in storage bins in moistureequilibrium with approximately 55 to 65% relative atmospheric humidityat ambient temperature or slightly above this temperature, in order toobtain a stabilized product without residual stresses. All that isdecisive is that diffusion processes and the surrounding atmosphere leadto no significant moisture quantities being removed from the finishedproduct, whilst maintaining the sought moisture content. The cooledproduct can then be cut to the desired length in conventional manner.

The process according to the invention can be carried out withparticular advantage with the single-level drier subdivided between therapid heating zone and an intense drying zone.

The basic principle of the invention offers a large number of advantagesand in particular allows many further combinations. The air and climatecontrol can take place in a planned manner by means of the single-leveldrier, particularly if the air circulation is at right angles to thedirection of movement of the long product. The climate can be randomlyfinally controlled and regulated with advancing drying processes withrespect to all the parameters, such as air speed, air moisture contentand air temperature. This also makes it possible for the first time tohave a design with complete automation, i.e. with the automatic controlon the basis of the conditions required by the product. It isparticularly advantageous to combine the single-level construction withso-called turbo-air guidance. The single-level drier also permitsautomatic product monitoring for the first time, e.g. by measuring theproduct moisture content and/or colour, both in the rapid heating zoneand in the intense drying zone. Preferably, the rapid heating zone andthe intense drying zone are equipped with an air circulation system insuch a way that the air is passed through the product vertically fromtop to bottom or from bottom to top.

It has proved particularly advantageous to control the air with theaforementioned turbosystem by means of an air compressor and/or fan.Control is preferably by a central computer and controlled in this wayis blown into the individual climate zones of the rapid heating zone andthe intense drying zone. The rapid heating zone and intense drying zoneare preferably equipped with longitudinal ducts for fresh air and spentair. In this arrangement, this makes it possible to so regulate theclimate in each stage of the rapid heating zone and intense drying zone,that the corresponding climatic conditions can be regulated in anoptimum manner. Thus, according to the invention, there can be nooverpressure or underpressure in the drying zone or the individualsections.

The apparatus according to the invention with devices for controllingthe climatic conditions in the individual circulating air zones, as wellas rest zones, is achieved by a planned fine dispersion of the supplyair and the controlled removal of spent air from the individual climatesections using the corresponding longitudinal ducts. For regulating thesupply or spent air stream, the apparatus has connecting ducts withrespect to the longitudinal ducts with controllable pressure regulatingmeans for the zonal climate control in the sense of the aforementionedturbo-system.

It is advantageous if the apparatus having a rapid heating zone and anintense drying zone is supplied with circulating air for fresh and spentair and has throttle and control flaps, as well as a fresh and/or spentair heating device for preventing condensate formations. It is alsofavourable if the fresh air-spent air system can be short-circuited forclimatic preparation, control and extension. It is also appropriatewithin the sense of the invention for the apparatus to be preferablyequipped with steam moistening controlled by the central computer forcontrolling and regulating the individual climatic or climates of therapid heating and intense drying zones.

For optimizing the system, the longitudinal ducts of the rapid heatingzone and the intense drying zone have adjustable slides in eachventilated element.

As described hereinbefore, to ensure an optimum control of the dryingzones for the spent air and fresh air, a turbo-system superimposed onthe circulating air is used with particular advantage. It is appropriatefor the arrangement of this system in the apparatus according to theinvention for energy reasons and in view of the aforementionedcondensation problems if the longitudinal ducts of the turbo-system forspent and fresh air are arranged in the drying chamber of thesingle-level drier. In an optimum arrangement of the apparatus accordingto the invention air mixing units, heating elements, compression andsuction units of the turbo-system are incorporated into the spent andfresh air ducts within the drying chamber of the single-level drier.Thus, energy losses are reduced to a minimum.

It can be appropriate from the mechanical and operational standpointsfor the air mixing units, heating elements, as well as compression andsuction units of the turbo-system to be arranged in ducts outside thedrying chamber. It is obvious that these elements are correspondinglyinsulated, in order to prevent or exclude heat losses.

The aforementioned rapid heating zone is also of particular importancefor the invention and preferably has one or more zones at differenttemperatures. Reference is made to temperature jump sections withtemperature jumps of approximately 4° to 12° C. These temperature jumpsections are set in such a way that between adjacent climates atdifferent temperatures, there are no so-called dew point zones andconsequently no condensate formation in the various circulating airzones or conditions, so that the undesired wetting of the product to bedried is prevented.

As a result of the inventive concept, it is now possible to completelyutilize the technological possibilities of the process for producingpasta products and to improve them in such a way that, whilst retainingthe high quality requirements made on the process product, asubstantially troublefree, simple and economic process control can beachieved. In order that this can be achieved at the selected hightemperatures and with the short production times, preferably productmeasuring and monitoring equipment is used, which are e.g. evaluated bymeans of a central computer and used for automatically regulating thedrying parameters. This obviates the need for the dough expert to carryout routine checks.

In order that the product to be dried can be subject to checks andinspections, in the rapid heating and/or intense drying done isappropriately provided an automatic bar removal means which removes theproduct from the single-stage drier in such a way that in the vicinityof the rapid heating zone and in the intense drying zone, there is atleast one automatic bar removal means. This automatic removal of a barfrom the single-level drier permits an exact, controlled monitoring ofthe product. To ensure that there are no undesired product losses (theproduct on the bar can amount to 3 to 6 kg) and so that there is no holein the product during the further process sequence and so that theproduct of the same bars can be checked a number of times, the barremoval means preferably has an automatic bar return to thecorresponding zone.

It is particularly advantageous with a view to a more extensiveautomating of the overall apparatus, if the automatic bar removal meanshas product measuring and/or monitoring equipment for the productquality for controlling or regulating the drying parameters (climate).

The corresponding arrangements of the bar removal means are shown inFIG. 4, relative to position 28 and at the top right positions 35/36/37.A tappet hook 35 takes up a suspended bar from the single-level drier.The long product 37 is checked in the rest state with measuring device36 with respect to the desired product parameters (temperature,moisture, colour, starch, protein, ash, etc). If the bar is returned, itremains on the tappet hook 35. The checks are made, whilst a sample istaken for the laboratory and this can also take place automatically.Following the checks, the bar is returned to its position in the processand is optionally controlled again in a further drying portion.

The advantages linked with the invention are in particular that it ispossible for the first time to obtain high quality long products, inmuch the same way as in the bread baking oven, at least in the main partof the drying, in a one-level, elongated drying tunnel, withoutproviding the previously described rest zones. The process control isroughly 4 to 8 times shorter than in the prior art processes. As in thiscase all the bars of the bar attachment means are moved in the sameforward direction, few breakdowns occur. This is due to the fact thatmost of the bar transitions and reversals are eliminated. This permits acontinuous process control, because the climate in the individualclimate zones can be locally better controlled. There is also an energysaving, if the heated, climatically controlled bar attachment means ispositioned as the first section directly upstream of the first climatezone or the rapid heating zone. The climate in the representedindividual climate zones can be optimally adapted by mixing, heating ormoistening to the necessary extent, air being usable in a maximum manneras a carrier of heat and moisture. Thus, the complete drying process canbe controlled in a very economic manner, a plurality of easily performedmeasures permitting an optimum adaptation and utilization of theparticular circumstances. A process product is obtained, which satisfiesthe highest quality requirements. It has an attractive colour, excellentbiting and cooking stability, as well as minimum slime formation duringcooking. The process according to the invention will be technologicallyillustrated hereinafter with respect to these advantageous properties ofthe process product and reference will be made to a number of fewfindings.

The present invention has led to a number of new and valuable findings,particularly a general clarification of the production of long products.The vital point for all the physical tests (feel in the mouth, bitingstability, taste, colour, etc) for all traditional foods is maintainingthe customary quality. It is difficult for humans to digest raw cerealstarch. Therefore, bread is baked and pasta products are cooked. Theprotein is denatured during baking and cooking, so that it can be leftto the economic control of the operation as to which industrial processstage is used for the complete or partial denaturing. It has proved veryimportant for an optimum final quality and for a problem-free drying ofthe pasta products that the best possible protein network is produced atthe time of dough preparation and compression. This is achieved in thatat the compression pressures in the press, a temperature ofapproximately 50° C. is not exceeded. If the long product leaves thepress at e.g. 45° C., the gluten protein is still "live", so that it ispossible to fully utilize the reactivity inherent in such a protein inorder to build up a very fine-mesh, three-dimensional protein network.The prerequisite is that no mechanicalthermal deformation forces act onthe dough parts, the dough strands being hung on the bars immediatelyfollowing the pressing process and they remain there until they aresufficiently dried and then notonly is the protein network fullymaintained but, as tests have shown, is formed to an even more intenseextent if the drying is terminated in less than roughly 2 hours e.g.substantially between approximately 80° and 100° C. The final phase ofstabilization, during which 1 to 2% moisture is removed, leads to nodisadvantages, because temperatures below roughly 65° C. are used and inpart circulating air.

Gluten protein starts to coagulate at temperatures above approximately50° to 60° C. The press-warm long products (approximately 45° C.),preferably directly following the pressing process, are heated for 15 to30 minutes and 65 to 75% relative humidity to above 80° C. and thendried to a moisture content of approximately 14% at e.g. approximately85° to 95° C., so that the protein network is made firm or strengthened.The cooking characteristics are improved and these pasta products arenot easily damaged by cooking. The starch is only dissolved out to aminimum extent during the cooking process and the biting stabilityremains good.

The gluten network prepared in the press gives an adequate strength as aresult of the coagulation of the long product with drying to ensure thatthe dough strands do not break off from the bars as a result of theirown weight.

Although according to the invention, the hitherto necessary encrustingof the partial surface is completely avoided and the starch has reducedcohesiveness at higher temperatures, this surprisingly leads to nodisadvantage. Research has shown that in the case of rapid, but notexcessively rapid drying in the heating zone, there is a permanentchange or restructuring of the internal binding forces. Immediatelyfollowing the press, there is a uniform structure of the protein orgluten network and starch granules, as well as finely dispersed water.The gluten network can be compared at this stage with a rubber body,i.e. an elastic body. However, during longer heat action, correspondingto the boiling of eggs, its strength increases as a result of thecoagulation process. The protein coagulation problem also occurs whenproducing "egg soup". The starch corresponds to a crystalline substance.The still live protein and the high proportion of water give the freshlypressed long product a moistplastic behaviour. With increasingtemperature, the crystalline structure of the starch is loosened and thehydrogen bonds are also loosened. However, an adequate strength remainsdue to the advancing drying process.

Through the avoidance of dry crusts on the dough surface, the poresremain free through to the dough surface, so that in the hightemperature range (e.g. 80° to 100° C.) the loosening of the hydrogenbonds, linked with the softening of the starch structure, can beutilized for rapid drying, without requiring very large vapour pressuredifferences between the product and the drying air during the maindrying. The best values were obtained with a relative atmospherichumidity of approximately 70 to 80%.

Microscopic sections with corresponding colours have also shown thatlong products produced according to the invention are subject to notasting and also no disturbing starch change and in particular have alargely set protein network and a quality which is equally as good asthe best hitherto obtained long products. This is surprising because thebiological, chemical and physical processes between the raw dough andthe dried pasta product are recognised as being extremely complex. Astarch granule generally has a diameter of 5 to 50 μm, the thickness ofe.g. spaghetti is between 1.6 and 2.5 mm. In the case of good quality,it is required that also in microscopic section, the characteristics ofthe pasta product are uniform from the centre to the outermost marginalarea, with no crack or bubble formation, which would lead to damageduring prolonged storage. Pasta products are a standard stockpilingproduct for emergency supplies. The invention offers special advantageswith regards to hygienic and microbiological questions and the treatmentcorresponds to an excellent pasteurization.

The invention has in particular provided a definite clarification of thebiochemical process in pasta product production. In the early times ofpasta product production, it was necessary to accept drying times ofsometimes several days, with ambient temperatures of less than 50° C.,together with a difficulty controllable acid fermentation which, iflactic acid is only formed in trace form may be attractive to thegourmet, but often led to inferior and excessive "acid" pasta products.The further additional enzymatic oxidation reactions in the direction ofenzymatic browning and colour decomposition are completely undesired.Such climatic conditions are also an ideal incubator for bacteria,including pathogenic agents, such as salmonella and staphlcocci.However, on maintaining the drying process for too long at temperaturesover 70° C., the Milliard reaction occurred, in much the same way aswhen baking or roasting and when baking bread and which led to a browncolouring. However, in carrying out the complete production process atbetween 81 and 100° C. with the product in the moist state, yellowpigments came to bear and provided the long product with an attractiveappearance. In addition, this treatment in this temperature range has apasteurizing effect on the product. However, this presupposes completelycontrolled conditions throughout the production process, in accordancewith the present invention. The essential point is the automatic controlof each climate zone, so that the conditions according to the inventionare strictly adhered to. It is particularly advantageous for the longproduct to be guided at a moisture content of less than 18% andpreferably less than 14% in one level through a longitudinal movementthrough the different climate zones. The air flow in the various climatezones is zonally directed perpendicularly to the long product in such away that part of the air is introduced and removed by ducts forcontrolling the climate of the individual climate zones passing insideand/or outside the drying chamber in the sense of a turbo-system.

Due to the fact that, according to the invention, the soft,moist-plastic pasta product is very rapidly brought to a temperature ofmore than approximately 80° C. without any significant drying and isthen dried there within a short time, no cracks, stresses or bendinghave occurred on the long product. Thus, the individual dough strandsthereof remain absolutely straight, because a bent product would besusceptible to breakage. In addition, in the case of irregularities, itwould have a greater risk of the individual dough strands stickingtogether.

The invention is described in greater detail hereinafter relative to thedrawings, wherein show:

FIG. 1 diagrammatically, a longitudinal view of the apparatus accordingto the invention with a rapid heating zone equipped with chargingvalves.

FIG. 2, as FIG. 1, but with a charging valve-free rapid heating zone.

FIG. 3 the configuration of the drying curves in the known process andin the process according to the invention, in the form of a graph.

FIG. 4, as FIG. 2, but with modifications (bar removal) means, as wellas supply and spent air system).

FIG. 5 diagrammatically, a monitoring, control and regulating means forthe apparatus according to the invention.

According to FIGS. 1 and 2, the raw material in the form of grits, waterand eggs is introduced by means of a dosing mechanism 1 into a mixingtrough 2, from where the pasta product is fed into a long product press3 with a press drive 4. On leaving the long product press 2, the longproducts, e.g. spaghetti, are brought into the desired form and are cutto the desired length of e.g. 30 to 50 cm by means of a cuttingapparatus 6. The still not complete long products or pasta productstrands leave the mould 5 at a temperature of approximately 40° to 50°C. In order that at this point there is neither a sticking, nor acooling of the long product, the latter is passed directly through aninlet duct 7 into a conditioned attachment means 8. Between inlet duct 7and attachment means 8 is provided a fan 9, through which heated air isblown against the product. From attachment means 8, the long productpasses into a feed element 11, in which once again heated air is blownagainst the product by means of fan 10. From here, the long product ispassed into a rapid heating zone 12, 13, 14, 15, 16 and subsequently tothe main drier 17, which has a plurality of ventilated elements.

As a function of the desired drying temperature in the main drier 17,the product can be brought to 90° to 120° C. in a varying number oftemperature jumps of initially e.g. 40° C.

The apparatus according to the invention, whose essence represents anovel long product drier, has as its main feature a long, continuous,single-level drying tunnel. Corresponding to the movement of the loaf inan industrial continuous baking oven, the long products, suspended onbars, move in the longitudinal direction. However, the air is blown fromtop to bottom or bottom to top through the drying tunnel. Each climatezone is equipped with a temperature and moisture probe 8 and isregulated with a central, microcomputer-controlled climatic regulatingmeans 19 in order to maintain the desired conditions in the dryingstage. For this purpose, it is necessary to regulate the desiredtemperature by means of heat exchangers 29 and the desired atmospherichumidity by means of vapour or fresh air in each drying section. Iflarge climatic jumps are necessary, then elements with charging valves13, 15 (FIG. 1) could be provided in the heating zone.

At the end of the main drying, there is a charging valve 20, followed bya cooler or shape stabilizer 21. The end of the complete drying line isformed by a cutting machine 22, the product then being supplied to thepacking machines.

In order to ensure an optimum control of the drying zone, as shown inFIGS. 1 and 2, a so-called turbo-system is particularly advantageouslyused for the fresh and spent air and for this purpose ducts 23 and 24are provided in the rapid heating zone. Through the automatic control ofthe air flaps 25, the fresh and spent air quantity can be controlled insuch a way that there is no overpressure or underpressure, which couldlead to an undesired influencing of the climate in adjacent zones. Inthe multi-element main drying zone 17, the turbo-system is supplementedby an air system, in order to regularly distribute the conditioned freshair over the entire length of the drier. Ducts 23' and 24' arepositioned within the drier and are externally interconnected. Part ofthe climatically controlled drier air circulates in the said ducts andis prepared by means of fresh air and water vapour. This air can bedistributed by means of slides 26 in a uniform manner over the entirelength of the drier, even if the latter is very long. It is alsopossible to dry this circulating air by condensation, instead ofsupplying fresh air. This can bring about a heat recovery and acorresponding reduction of energy consumption. It is important forhygienic reasons that the point where the condensation water occurs ispositioned outside the drier.

In order to optimize the process, the climatic conditions of the variouszones should be set at the beginning of production. For this purpose,nozzles 27 are provided for injecting vapour or steam. In order topermit a control of the drying process, there is an automatic productremoval means 28 between the rapid heating zone and the main dryingzone.

If for quality reasons, the product is to be completely dried attemperatures below approximately 80° C., a separately regulated finaldrying zone can be provided following the main drying zone. This dryingzone could comprise a single-level drier or also a three-level drier andin each case a sensor is provided at the end of drying.

FIG. 4 shows the apparatus of FIG. 2 with modifying supplementary means.A special configuration of the removal means is illustrated by position28 and at the top right positions 35, 36, 37. A detailed explanation ofposition 28 has already been provided. As a result of means 31 and 33,fresh air is supplied to the system for preparing the climate,accompanied by heating by element 34. The spent air is removed by means30, 32. As a result of this regulatable system, it is possible toprevent the formation of underpressures or overpressures in the system.

In FIG. 5, individual process sections are indicated by correspondingblocks, process zone 1 representing the raw material preparation(controlled raw material mixing) of grits, water and other additives, aswell as the dosing or metering thereof. The dough preparation of processzone 2 mainly covers the mixing, pressing and moulding. The freshlypressed product is automatically hung on bars and introduced intoprocess zone 3, which represents the rapid heating zone. Process zone 4represents the actual intense drying. In process zone 5, thesubstantially completely dried long product is stabilized and isautomatically filled into domestic packs or other packs.

A regulator 40₁ -40_(n) is systematically represented for each processzone. In fact, each individual zone may have a plurality of suchregulators, which are combined into an auxiliary computer, optionallycoupled to the plant control and locking means 50 and can at least beconnected for information flow purposes.

The main computer 47 is constantly connected to a set point store 46 forthe filing of individual data and/or programs and for removal thereof.To main computer 47 are also connected measuring devices 42_(l) -42_(n)(or, as in FIG. 4, position 36, product measuring and monitoring means(M) for the product temperature, moisture, colour and product starch,together with protein ash, etc). A set point indicator 41_(l) -41_(n)for a complete or partial manual operation can also optionally be usedin conjunction with measuring means (M).

It is also very important for the signal lines S_(l) -S_(n) connectedfrom the individual process zones to the main computer 47 to be at notime interrupted. However, the control lines from the main computer tothe regulators 40_(l) -40_(n) or process zones 44_(l) -44_(n) areprovided with reversing switches 45_(l) -45_(n) or 48_(l) -48_(n) forswitching over purposes. A central point of the installation is theinteraction of the individual installation elements with the electronicor computer means on the one hand, as well as the dough expert on theother, who can counteract the daily occurring variations as a result ofhis experience and knowledge of the product and equipment specialities.

Operation can be controlled in the following way. On putting intooperation for the first time, all the equipment elements are put intooperation in accordance with the locking system. The individual controlloops (for regulating the air quantity, moisture, temperature, etc) arethen successively manually optimized. The corresponding data are fedinto the main computer 47 or the set point store 46 for fixing the setpoint diagrams (e.g. punched cards).

Production is started by controlling the corresponding production supplyand/or dosing elements. On the basis of empirical values, the controland regulating circuits and loops linked with the product parameters areroughly set. The corresponding values can once again be supplied to theset point store 46 or the main computer 47. On the basis of said data,the complete starting production with the corresponding starting programis controlled. At the end of the starting phase, which can e.g. last 1to 4 hours, the dough expert starts to check the complete productionprocess. He then optimizes the product, air and/or climatic parametersin the apparently relevant or necessary process sections. For thispurpose, he interrupts the corresponding control line of main computer47, e.g. to process zone 3, by interrupting the switching contact 45₃.Regulator 3 continues with the set point given prior to the interruptionof the control line. The dough expert now supplies an improved set pointby corresponding supply to regulator 3 or one of the regulators inprocess zone 3. The best set points are once again fed into the maincomputer or set point store for correction purposes. Reversing switch45₃ can now be closed again and the corresponding group of regulatorscan be controlled with the new set points. Optimizing manipulations onthe part of the dough expert can be carried out at any time bycorresponding operation of reversing switches T_(l) -T_(n) or 45_(l)-45_(n). It is decisive for this procedure that simultaneously with thefixing of the set point diagrams for the process parameters, theassociated diagrams are associated with the input parameters, such ascapacity (kg/h), nature and mixture of the raw material (durum, hardand/or soft wheat), water addition and various additives (egg, salt,etc), well as the parameters for the product quality (moisture, colour,strength, etc).

If now all the parameters with respect to the entry and removal of theproduct, as well as all the parameters with respect to the processcontrol are to be determined and established in the set point store, fora repeat of the same product quality, it is possible to call up and usefor the new production the set points or desired values previously foundas being optimum. This applies for the starting, production andcompletion diagrams. Thus, the dough expert can much more reliablycontrol the long product line, the computer means, regulators andmeasuring devices representing valuable aids. He can at any timemanually control any point in the process through disconnecting theelectronic automatic means, or alternatively he can allow the plant tooperate automatically for long periods. In special situations oremergencies, the dough expert can control the complete plantsemiautomatically, without linking the process zones via computer means.It is thereby important that he can rely on the plant control andlocking.

The individual curves of FIG. 3 can be interpreted as follows. In theold system, the long products are on average dried for approximately 14or more hours at 50° C. and in the practised prior art for 10 hours atan average temperature of 65° to 75° C. When using the process accordingto the invention, it ispossible to obtain a drying time of 1 to 31/2hours at an average temperature of 95° C. The very considerablereduction in product moisture content in the process according to theinvention compared with the conventional systems is very noteworthy.This can be attributed to the fact that in the process according to theinvention, during drying, the pasta or long product surface is notencrusted once or several times and the long product dough strands,whilst still press-soft and not completely plasticized, are directlyconverted into a completely plasticized state and are kept therein atthe end of drying in the second heated climate zone. It is obvious thatin this plastic state, water expulsion can take place very rapidly.

We claim:
 1. In a process for producing long products with a moisturecontent of less than approximately 14% by weight, the long product beingformed in a press head and leaving the same in the form of soft,moisture-plastic dough strands which are guided in suspended manner upto the final drying through a series of different temperature, heatedclimate zones and, at the end of the drying process, the long productbeing subject to at least one of cooling and dimensional stabilizationin a further climate zone, the improvement comprising the stepsof:heating the long product leaving the press head as rapidly aspossible in a first climate zone, but for more than 10 minutes, to atemperature in the range of approximately 80° C. to 140° C. under theaction of a heating medium with a relative humidity of approximately 60to 80%, so that drying of the product in the first climate zone isminimized, said drying step being performed in a plurality of stageswithin said first climate zone, each stage being defined by apredetermined temperature jump, with the dew point of each stage beingmaintained below the temperature of the immediately preceding stage, anddrying said product in a second climate zone under te action of a dryingmedium with a temperature of over approximately 80° C. and a relativehumidity of approximately 65 to 85% to a moisture content of less thanapproximately 14% by weight.
 2. The process according to claim 1,wherein, in the first climate zone the long product is heated for about15 to 60 minutes at a relative humidity of the heating medium of about65 to 75%.
 3. The process according to claim 1, wherein in the secondclimate zone, the long product is heated for about 30 to 120 minutes ata relative humidity of the drying medium of about 70 to 80%.
 4. Theprocess according to claim 1, wherein the long product is guided insubstantially one tier by a longitudinal movement through the differentclimate zones.
 5. The process according to claim 1, wherein fresh air isblown into the long product drier by means of a turbo-system.
 6. Theprocess according to claim 4, wherein the air flow in the differentclimate zones is zonally directed at right angles to the long productsand part of the air is introduced and removed in the sense of aturbosystem by ducts for controlling the climate of the individualclimate zones and guided inside and outside the drying area.
 7. Theprocess according to claim 1, particularly for producing pasta productswith thermally unstable components wherein, in less than 1 hour, thelong products are intensely dried to a product moisture content of about18% and then for 1 to 4 hours and at a temperature of about 65° to 75°C. are brought to a final moisture content of less than 14%.
 8. Theprocess according to claim 7, wherein the products are intensely driedin less than about an hour to a product moisture content ofapproximately 18% and then, for 2 to 3 hours and at a temperature ofapproximately 65°-75° C., are brought to a final moisture content ofless than 14%.
 9. The method of claim 1 wherein said drying step isperformed by first drying the product at a temperature in the range ofapproximately 80° C. to 140° C. to an initial moisture content of lessthan about 18% by weight and then further drying at a lower temperatureto a final moisture content of less than about 14% by weight.
 10. Theprocess of claim 1 wherein the temperature range for said heating stepis approximately 80° C. to 120° C.
 11. The process of claim 1 whereinthe temperature range for said heating step is approximately 95° C. to120° C.
 12. The process according to 1, wherein said drying step isperformed by first drying the product at a temperature in the range ofapproximately 80° C. to 140° C. to an initial moisture content of lessthan about 18% by weight and then further drying at a lower temperatureto a final moisture content of less than about 14% by weight.
 13. In aprocess for producing long products with a moisture content of less thanapproximately 14% by weight, the long product being formed in a presshead and leaving the same in the form of soft, moist-plastic doughstrands which are guided in suspended manner up to the final dryingthrough a series of different temperature, heated climate zones, and atthe end of the drying process, the long product being subject to atleast one of cooling and dimensional stabilization in a further climatezone, the improvement comprising the steps of:heating the long productleaving the press head as rapidly as possible in a first climate zone,but for more than 10 minutes, to a product temperature in the range ofapproximately 80° C. to 140° C. under the action of a heating mediumwith a relative humidity of approximately 60 to 80%, so that drying ofthe product in the first climate zone is minimized, said drying stepbeing performed in a plurality of stages within said first climate zone,each stage being defined by a predetermined temperature jump, with thedew point of each stage biing maintained. below the temperature of theimmediately preceding stage, and drying said product in a second climatezone under the action of a drying medium with a product temperature ofover approximately 80° C. and a relative humidity of approximately 65 to85% to a moisture content of less than approximately 14% by weight. 14.The process according to claim 13, wherein, in the first climate zone,the long product is heated for about 15 to 60 minutes at a relativehumidity of the heating medium of about 65 to 75%.
 15. The processaccording to claim 13, wherein, in the second climate zone, the longproduct is heated for about 30 to 120 minutes at a relative humidity ofthe drying medium of 70 to 80%.
 16. The process according to claim 13,wherein the long product is guided in substantially one tier by alongitudinal movement through the different climate zones.
 17. Theprocess according to claim 13, wherein fresh air is blown into the longproduct drier by means of a turbo-system.
 18. The process according toclaim 13, wherein the air flow in the different climate zones is zonallydirected at right angles to the long products and part of the air isintroduced and removed in the sense of a turbo-system by ducts forcontrolling the climate of the individual climate zones and guidedinside and outside the drying area.
 19. The process according to claim13, particularly for producing pasta products with thermally unstablecomponents, wherein, in less than 1 hour, the long products areintensely dried to a product moisture content of approximately 18% andthen for 1 to 4 hours and at a temperature of approximately 65° to 75°C. are brought to a final moisture content of less than 14%.
 20. Theprocess according to claim 13, wherein said drying step is performed byfirst drying the product at a temperature in the range of approximately80° C. to 140° C. to an initial moisture content of less than about 18%by weight and then further drying, at a lower temperature, to a finalmoisture content of less than about 14% by weight.
 21. The processaccording to claim 13, wherein the products are intensely dried in lessthan about an hour to a product moisture content of approximately65°-75° C., are brought to a final moisture content of less than 14%.22. The process according to claim 13, wherein the temperature range forsaid heating step is approximately 80° C. to 120° C.
 23. The process ofclaim 13, wherein the temperature range for said heating step isapproximately 95° C. to 120° C.
 24. In a process for the manufacture oflong pasta by which the pasta strands are produced by a press head, hungon rods, heated, dried and finally cooled and stabilized as to form,comprising, for the purpose of shortening manufacturing time and forraising the product quality, the steps of:heating the pasta strandsstepwise to a product temperature of 80° C. to 100° C. by means ofheating medium with 60 to 80% relative humidity, and afterwards drying,in stages, with a product temperature of 80° C. to 100° C. and arelative humidity of the air of 65 to 85% until a product moisture ofunder 18% is reached, and assuring that in every level or every stage ofheating up and drying the processing air is heated up and circulated andadditionally in every step of every range a mixture of circulated andreadied fresh air is admitted under pressure and the pasta is processedin the length direction in a plane through all the steps.
 25. Theprocess according to claim 24, wherein, in a first heating climate zone,the long pasta is heated for about 15 to 60 minutes at a relativehumidity of the heating medium of about 65 to 75%.
 26. The processaccording to claim 24, wherein, in a second drying climate zone, thelong pasta is heated for about 30 to 120 minutes at a relative humidityof the drying medium of 70 to 80%.
 27. The process according to claim24, wherein the fresh air is blown into the long pasta dryer by means ofa turbo-system.
 28. The process according to claim 24, wherein the airflow in the different stages is zonally directed at right angles to thelong pasta and part of the air is introduced and removed by aturbo-system with ducts for controlling the climate of the individualstages and guided inside and outside the drying area.
 29. The processaccording to claim 24, particularly for producing pasta products withthermally unstable components, wherein, in less than 1 hour, the longpasta is intensely dried to a product moisture content of approximately18% and then for 1 to 4 hours and at a temperature of approximately 65°to 75° C. are brought to a final moisture content of less than 14%. 30.The process according to claim 24, wherein the products are intenselydried in less than about an hour to a product moisture content ofapproximately 18% and then, for 2 to 3 hours and at a temperature ofapproximately 65°-75° C., are brought to a final moisture content ofless than 14%.